Question

我已经放弃了尝试学习铁轨。我现在正集中精力尝试使用MERN堆栈开始使用节点。我已经完成了Stephen Grider和Andrew Mead的udemy课程以及所有代码学校的课程。我恐怕没有一个充满希望的开始。

我坚持让我的导入语句起作用。到目前为止，我试图导入文件。为此，我需要巴贝尔。我的package.json有：

"scripts": {
    "test": "mocha test/**/*-test.js --compilers js:babel-core/register --recursive",
    "start": "nodemon -w server.js server.js  --source-maps"
  },
  "author": "Ol",
  "license": "MIT",
  "dependencies": {
    "axios": "^0.16.1",
    "babel-cli": "^6.24.1",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-react": "^6.24.1",
    "babel-polyfill": "^6.13.0",
    "body-parser": "^1.17.1",
    "caniuse-api": "^2.0.0",
    "express": "^4.13.4",
    "lodash": "^4.17.4",
    "material-ui": "^0.18.0",
    "nodemon": "^1.11.0",
    "react": "^15.5.4",
    "react-dom": "^15.5.4",
    "react-promise": "^1.1.2",
    "react-redux": "^5.0.4",
    "react-router": "^4.1.1",
    "react-tap-event-plugin": "^2.0.1",
    "redux": "^3.6.0",
    "redux-devtools": "^3.4.0",
    "redux-form": "^6.7.0",
    "redux-thunk": "^2.2.0",
    "socket.io": "^2.0.1",
    "source-map-support": "^0.4.15"
  },
  "devDependencies": {
    "babel": "^6.23.0",
    "babel-core": "^6.24.1",
    "babel-loader": "^7.0.0",
    "babelify": "^7.3.0",
    "enzyme": "^2.8.2",
    "mocha": "^3.3.0",
    "react-addons-test-utils": "^15.5.1",
    "webpack": "^2.5.1"
  }
}

我的.babelrc有：

{
  "presets": ["react", "es2015"]
}

我的server.js有：

import express from 'express';
import bodyParser from 'body-parser';
import { MongoClient } from 'mongodb';
import 'babel-polyfill';
import SourceMapSupport from 'source-map-support';


SourceMapSupport.install(); //to get line numbers with file refs rather than compiled code line numbers


// const app = express();

app.use(express.static('open'));
app.use(bodyParser.json());

app.listen(3000, function(){
  console.log('listening on 3000');
});

我的webpack.config.js有：

module :{
    rules:[{
      // use : 'babel-loader',
      loader: 'babel-loader',
      query :{
        presets:['react','es2015']
        // ,'es2017'
      },
      test: /\.jsx?$/,
      exclude: /(node_modules|bower_components)/
    }]

当我尝试使用npm start时，我的import语句出错了。它说：

{ import express from 'express';
                                                              ^^^^^^
SyntaxError: Unexpected token import
    at createScript (vm.js:56:10)
    at Object.runInThisContext (vm.js:97:10)
    at Module._compile (module.js:542:28)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.runMain (module.js:604:10)
    at run (bootstrap_node.js:390:7)
    at startup (bootstrap_node.js:150:9)
[nodemon] app crashed - waiting for file changes before starting...

任何人都可以告诉我如何让babel设置与节点应用程序一起工作。我注意到即使我在我的控制台中运行npm install，我也没有在我的应用程序中获得node_modules文件夹。我使用yarn为package.json添加依赖项，但似乎没有能力生成node_modules文件夹。

下次尝试

然后我尝试了npm init然后npm升级（即使我使用yarn来添加模块）。

npm升级的输出如下，但我仍然没有得到节点模块文件夹。我认为babel无法识别我的导入声明的原因是因为我的应用中没有该模块。有谁知道如何在设置中创建节点模块文件？我以为这是自动发生的。

npm update
npm WARN deprecated isarray@2.0.1: Just use Array.isArray directly

> uws@0.14.5 install /Users/mlc/may/node_modules/uws
> node-gyp rebuild > build_log.txt 2>&1 || exit 0

- ms@0.7.3 node_modules/engine.io-client/node_modules/ms
- debug@2.6.4 node_modules/engine.io-client/node_modules/debug
- ms@0.7.3 node_modules/finalhandler/node_modules/ms
- react-addons-create-fragment@15.5.4 node_modules/react-addons-create-fragment
- react-addons-transition-group@15.5.2 node_modules/react-addons-transition-group
- ms@0.7.3 node_modules/socket.io-client/node_modules/ms
- debug@2.6.4 node_modules/socket.io-client/node_modules/debug
- camelcase@1.2.1 node_modules/uglify-js/node_modules/camelcase
- cliui@2.1.0 node_modules/uglify-js/node_modules/cliui
cr@1.0.0 /Users/mlc/may
├── axios@0.16.2 
├── body-parser@1.17.2 
├── express@4.15.3 
├── material-ui@0.18.2 
├── mocha@3.4.2 
├── react-promise@1.1.3 
├── react-redux@5.0.5 
├── socket.io@2.0.2 
└── webpack@2.6.1

Answer 1

使用presets: ["es2015", "react", "stage-2"]。

如果要使用导出和导入来运行server.js，请添加babel-node。

<强>的package.json

...
"start": "cross-env NODE_ENV=production babel-node server.js",
"dev": "nodemon server.js --exec babel-node --presets es2015,react,stage-2"
...

<强> .babelrc

{
  "env": {
    "production": {
      "presets": ["es2015", "react", "stage-2"]
    },
    "development": {
      "presets": ["es2015", "react", "stage-2"]
    }
  }
}

Babel配置在MERN应用程序中

1 个答案: